With the particle system,when I render the carpet I see no bristles,but I see them in object mode
Because of applying scale to copied and scaled rug, your settings become wrong. To obtain the same result in toilet file as in carpet file, you would need to increase number of particles, hair length and thickness in particle settings. I can't give you exact numbers, cause it would require some experimentation.
In the meantime, what you can do fast and easy way, is to delete the carpet and copy it again from the carpet file, but this time only scale it without applying the scale. This way you'll get exactly the same look without changing settings.